Subject: RE: [PWE3] draft-ietf-pwe3-fc-encap-06.txt Last Call

From: [email-masked]
Date: Fri, 18 Jan 2008 01:15:32 -0500

The -07 version of the FC-PW draft addresses most of the
congestion control issue around CIR.  There are still a
few small things to clean up:

(1) A reference needs to be cited for R_A_TOV and a sentence
should be added to stat that the default value of R_A_TOV is
10 seconds.  R_A_TOV is defined in section 20.2.1.4 of FC-FS-2:

[FC-FS-2] "Fibre Channel Framing and Signaling-2 (FC-FS-2)",
		ANSI INCITS 424:2007, August 2006.

(2) The PW status of "Bandwidth resources unavailable" is
defined by draft-ietf-pwe3-dynamic-ms-pw.  This raises
a couple of concerns:
- The dynamic-ms-pw draft defines that PW status for PW
	setup failure when the requested bandwidth resources
	for the PS aren't available, and hence the PW can't
	be created.  That status code is being used here for
	loss of bandwidth after the PW is up and running.
	I'm not sure whether that's a good idea, vs.
	defining a new PW status code.
- The IANA registration of that PW status code is
	temporary because the dynamic-ms-pw draft is still
	in the pwe3 WG.  If that PW status is to be re-used,
	a normative reference to the dynamic-ms-pw draft
	appears to be needed from the FC PW draft.

Thanks,
--David
----------------------------------------------------
David L. Black, Distinguished Engineer
EMC Corporation, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953             FAX: +1 (508) 293-7786
[email-masked]        Mobile: +1 (978) 394-7754
----------------------------------------------------

> -----Original Message-----
> From: Black, David 
> Sent: Tuesday, October 23, 2007 2:37 PM
> To: [email-masked]'; pwe3
> Cc: Danny McPherson; Black, David
> Subject: RE: [PWE3] draft-ietf-pwe3-fc-encap-06.txt Last Call
> 
> This draft has congestion control issues.  The authors should be
> commended for use of TFRC, but TFRC is used with an absolute rate
> floor called the Committed Information Rate (CIR).  When CIR > 0,
> the FC PW behaves like a fixed bandwidth PW up to the CIR (uses
> CIR bandwidth regardless of losses), and is TCP friendly only
> for the bandwidth that exceeds the CIR.
> 
> This is a potential problem if the network capacity has fallen
> to the point that the use of CIR bandwidth by the FC PW is a
> contribution to congestion - that CIR bandwidth usage is
> non-reactive to drops, e.g., the last sentence in Section
> 6.1.2 says:
> 
> 	The sender SHALL continue to transmit data at
> 	the CIR, as long as the conditions do not change (i.e.,
> 	the network continue being congested).
> 
> In other words, the FC PW will continue to send traffic at the
> CIR no matter what the network conditions.  I believe the recent
> discussion about what could be done for congestion control for
> fixed- bandwidth/non-reactive pseudo wires applies to the
> FC PW usage of CIR bandwidth.  To start with, see:
> 
> http://www1.ietf.org/mail-archive/web/pwe3/current/msg09208.html
> 
> Thanks,
> --David
> ----------------------------------------------------
> David L. Black, Senior Technologist
> EMC Corporation, 176 South St., Hopkinton, MA  01748
> +1 (508) 293-7953             FAX: +1 (508) 293-7786
> [email-masked]        Mobile: +1 (978) 394-7754
> ----------------------------------------------------
> 
> 
> > -----Original Message-----
> > From: Stewart Bryant [mailto:[email-masked]] 
> > Sent: Tuesday, October 23, 2007 8:23 AM
> > To: pwe3
> > Cc: Danny McPherson
> > Subject: [PWE3] draft-ietf-pwe3-fc-encap-06.txt Last Call
> > 
> > 
> > This is the start of WG last call for:
> > 
> > Encapsulation Methods for Transport of Fibre Channel 
> > frames Over MPLS Networks 
> > 
> > http://www.ietf.org/internet-drafts/draft-ietf-pwe3-fc-encap-06.txt
> > 
> > Last Call will end 9th November 2007.
> > 
> > Please read the draft and provide feedback to the list.
> > 
> > Thanks
> > 
> > Stewart
> > 
> > 
> > _______________________________________________
> > pwe3 mailing list
> > [email-masked]
> > https://www1.ietf.org/mailman/listinfo/pwe3
> > 
> > 

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